A worker with blood dripping from his head marked a low point in the tense, grinding life at a southeastern China factory used by Ivanka Trump and other fashion brands. An angry manager had hit him with the sharp end of a high-heeled shoe.

Workers from the factory, including one current and two former employees who spoke to The Associated Press, reported overtime that stretched past midnight, steep production quotas and crude verbal abuse at Ganzhou Huajian International Shoe City Co. They said beatings were not unheard of, but the shoe attack, which all three say they witnessed last year, was violent enough to stand out.

“He was bleeding right from the middle of the head,” the current worker said.

“There was a lot of blood. He went to the factory’s nurse station, passing by me,” said a second man, who said he quit his job at Huajian because of the long hours and low pay.

The three workers are the first people with direct knowledge of conditions at the Ganzhou factory to speak with the media. All three spoke to the AP on condition of anonymity, for fear of retribution or arrest.

Last month, three men investigating conditions at the Huajian Group factory in Ganzhou were detained, accused of illegally using secret recording devices to steal commercial secrets. They, like one of the three men AP spoke with, worked with China Labour Watch, a New York nonprofit that has been investigating Ivanka Trump’s Chinese suppliers for more than a year.

Li Qiang, founder of China Labour Watch, describes Huajian’s Ganzhou factory as among the worst he has seen in nearly two decades investigating labour abuses. His group says pay can be as low as a dollar an hour, in violation of China’s labour laws. According to China Labour Watch investigators, until recently, workers might get only two days off – or less – per month.

China Labour Watch said the company forced workers to sign fake pay stubs with inflated salary numbers and threatened to fire workers if they didn’t fill in questionnaires about working conditions with pre-approved answers. Workers also said the company pressured people not to speak with outsiders about conditions at the factory.

In comments to the AP, the Huajian Group declined to respond to specific questions, but broadly denied all allegations, calling them “completely not true to the facts, taken out of context, exaggerated”. The company said it operates lawfully and that China Labour Watch “invented so-called ‘facts” by illegal means of buying undercover work, which has already affected the enterprise’s normal business seriously and affected the survival and employment of tens of thousands of staff”. The company noted its significant contribution to the economy and to society, particularly through its employment of disabled people.

Before taking on an official role as adviser to her father, Ivanka Trump stepped back from day-to-day management of her brand, but she has retained her ownership interest. She has not commented on the detentions or the reports of poor working conditions at one of her brand’s suppliers. Her spokeswoman declined to comment for this story.

Abigail Klem, president of the Ivanka Trump brand, said “the integrity of our supply chain is a top priority and we take all allegations very seriously”. The company says its products have not been made in the factory since March, but China Labour Watch said it had an April production schedule indicating that nearly 1,000 pairs of Ivanka Trump shoes were due in May.

In the past, some brands have used China Labour Watch’s reports as a tool to help keep their supply chains clean. Walt Disney Co., for example, investigated and ultimately decided to sever its relationship with at least one supplier following reports of poor conditions, and sought to improve labour practices at others.

China Labour Watch outlined its findings in letters sent in June to Ivanka Trump at the White House and to other brands. So far, the group says it has gotten no response.

The group said it also sent Ivanka Trump a video taken inside the factory in May. That video included a clip in which a manager threatened to rough up a worker who had apparently arranged shoes in the wrong order.

“If I see them f–ing messed up again,” the manager yells, “I’ll beat you right here.”

The video has not been released to the public, but it was shown to AP at China Labour Watch’s office in New York.

Marc Fisher, which has made shoes for Ivanka Trump and Easy Spirit at the Ganzhou factory, has said it would look into the allegations.

G-III Apparel Group, which produces shoes for Karl Lagerfeld, said it had not received a letter but “fully supports the independent monitoring of global supply chains”.

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“When workplace safety and fairness issues are brought to our attention, we take them very seriously and work with our partners to resolve them,” G-III spokesman Chris Giglio said in an email.

Ann Taylor spokesman Shawn Buchanan also said the company takes the allegations “very seriously” and is “actively conducting an investigation to assess this facility’s compliance with our code of conduct and applicable laws and regulations”.

The Kendall & Kyle brand said its “footwear manufacturer works with many footwear production factories and all factories are required to operate within strict social compliance regulations”.

Other brands identified by China Labour Watch as customers of the Ganzhou factory include Nine West, Naturalizer and the Camuto Group, which makes shoes for BCBG Max Azria, Jessica Simpson and Tory Burch. None responded to requests for comment.

The current Huajian employee who spoke to the AP said life at the factory has changed since the arrests of the three investigators brought the glare of public attention.

Overtime was radically reduced this month, he said. Shifts used to run from 7.10am until after 9pm or 10pm, and sometimes after midnight, with two daily breaks, he and a former employee both said. But for the last few weeks, workers have been released before 7pm.

They’re also starting to get every Sunday off, which is standard under Chinese labour law, said the current employee, who also moonlights for China Labour Watch.

City government officials turned up recently, he said, and the factory gave everyone an egg to eat in the middle of their afternoon shift.

Life inside Ganzhou Huajian is focused on a single number: the monthly quota of shoes that must be produced, according to China Labour Watch investigators and workers. A single production line of 50 workers may need to produce close to 30,000 pairs of shoes, depending on seasonal demand, the current employee and one former employee told AP.

Those who miss their targets do not collect the full salary, said the current employee.

“It is impossible to meet the target, actually, because it just keeps on going up,” the former employee said.

The new abbreviated working hours are a mixed blessing, the current employee said, because they haven’t been able to meet production targets.

Huajian, meanwhile, has been moving production to Ethiopia, where workers make around $100 a month, a fraction of what they pay in China, according to Song Yiping, a manager at Huajian’s Ethiopian factory, who spoke to the AP in January. He said he’s heard President Trump talk about bringing jobs back to America, but he doubts that will happen with shoes. Even Chinese vocational school dropouts don’t want to work for Ethiopian wages.

“The American clients push down the price,” Song explained. “Consumers want to buy cheaper shoes.”